Machines for abrading sheet material



A ril 7, 1964 D. s. HALL ETAL MACHINES FOR ABRADING SHEET MATERIAL Filed Feb. 5, 1965 nited States atent Gffice 3,127,711 Patented Apr. 7, 1964 3,127,711 MACHINES FOR ABRADTNG SHEET MATERIAL Dennis S. Hall and Michael J. Roberts, Leicester, England,

assignors to United Shoe Machinery Corporation, Flemington, N.J., a corporation of New Jersey Filed Feb. 5, 1963, Ser. No. 256,446 Ciairns priority, application Great Britain Feb. 16, 1962 Claims. (Cl. 51-435) This invention relates to improvements in machines for abnading work pieces of sheet material. More particularly the invention is directed to a machine of the type described in United States Letters Patent No. 2,674,- 833 which is used commonly for scouring articles such as outsoles, insoles, top pieces and the like made of leather, rubber or synthetic materials.

While machines constructed as described in said patent have proved generally successful in operating on work pieces of materials having substantial stiffness, the introduction of flimsy insoles or soles of materials of a very flexible nature, such as microcell-ular rubber, has presented a difficulty in that the trailing end of work pieces made from materials of this kind frequently becomes damaged. This due partly to the pressure of the feeding roll which is normally distributed over the full width of the sole being momentarily concentrated on the extreme tip of the sole and therefore pressing it more heavily against the abrasive tool. Such difficulty is also due to the extreme end of the sole being still pressed against the tool owing to the immediate drop ing of the feed roll after passing the highest point of the abrasive tool. This causes the end of the work piece to be seized by the abrasive surface and turned downward against the tool since such pieces have very little inherent stiflness by which to resist this tendency.

It is a general object of the invention to provide an improved machine for performing abrading operations on work pieces in which the aforementioned difiiculty is largely overcome. With this object particularly in mind the invention provides, in accordance with one of its several features, a machine for performing abrading operations on work pieces, having an abrasive tool, an endless band overlying said tool and acting to feed successive work pieces to the abrasive tool and press them thereagainst, said endless band being supported on a plurality of rolls journaled in a frame which is pivoted to enable the band to be raised and lowered to accommodate work pieces of different thicknesses between the tool and the band, and hydraulically operated means for varying the force with which the work piece is pressed against the abrasive tool.

In the illustrative machine the hydraulically operated means comprises a first piston and cylinder device which is arranged partially to support the weight of the frame and the-endless feed band rolls. The cylinder is connected, by a pipe for the transference of fluid, with a second piston and cylinder device, the arnangement being such that when the second piston is moved, corresponding movement is transmitted to the first piston, the effect being that, if sufiicient force is applied to the second piston the frame and feed band are raised. The second piston is urged by a spring, the force of which can be varied so that the frame is almost totally supported or totally unsupported by the spring. In this way the force with which the band presses against a WOIk piece as the work piece passes over the abrasive tool may be preset between a maximum value equal to the weight of the frame assembly and a minimum value which is almost nothing. The hydraulic pipe line is provided with a valve for restricting the passage of fluid from the first cylinder to the second when the frame is falling and allowing free passage of fluid in the opposite direction. The effect of this is to delay the falling of the fname and band when the trailing end of the sole passes the highest point of the abrasive tool and thereby to reduce the likeiihood of the sole being damaged.

The above and other features of the invention including various novel details of construction will now be described with particular reference to the dnawing and thereafter pointed out in the appended claims.

The drawing shows a right side elevation partly in section of the upper portion of a machine embodying the present invention.

The construction of the machine illustrated is generally similar to that described in said patent and reference is accordingly directed thereto for a description of the parts of the machine not hereinafter described in detail. As seen in the drawing, the machine includes a hollow column 2 in the upper ponti'on of which is journaled a transversely extending shaft 4 carrying an abrasive tool. The tool comprises a resilient roll 6 around which passes an endless abrasive band 8, the roll 6 being rotated at -a relatively high speed by a belt (not shown). The band 8 passes around a lower roll it which is journaled in a handled lever V12 pivoted at its rear end portion and urged in a counterclockwise direction about its pivot by a spring 14 to tension the abrasive band. The opening at the top of the column is substantially closed by a work table 16 which is pivoted on a shaft 18 journaled in upwardly extending lugs of a bracket 20 mounted on the rear of the column 2. The table is provided with an opening through which protrudes the highest point of the periphery of the abrasive tool.

For feeding a work piece past the abrasive tool and pressing it thereagains-t the illustrative machine also includes feeding mechanism supported in a frame 22 which is similar to the frame referred to as 30 in said patent and is pivoted on eccentric bushings 24 secured on the shaft 18. The feed mechanism comprises an endless resilient band 26 mounted on two resilient rolls 28, 30 by means of which the band is guided and tensioned as hereinafter described. The roll 2% is rotatably mounted in the frame 2 2 in a position immediately above the abnasive tool and is driven by .a chain and sprocket arrangement (not shown). The roll 30 is freely rotatable on a shaft 32 which is adjustably secured in rear end portions of side members 34 of an inner frame 36 which is pivoted on a spindle 33 of the roll 28. The inner frame 36 is of H-form when seen in plan, the members 34- being secured to opposite ends of a cross member 40. Open-ended slots 42 are provided in the rear end portions of the side members 34, in which the shaft 32 is positioned. Adjusting blocks 44, each having a tongue 46 which fits the open end of the slot 42, carry adjusting screws 48 which are threaded transversely into the end portions of the shaft 32 to provide adjustment of the tension of the feed band 26. The shaft 3 2. is secured in the adjusted position by a nut threaded on the end thereof by which it is clamped to the frame 36.

The feed band, as it passes under the roll 30, is prevented from contacting the surface of the table 16 by an eccentric headed stud 50 which is rotatably mounted in the frame 22, the head extending inwardly from the frame 22 so as to engage the underside of a projection provided on the inner frame as. A handle 52 is fixed on the outer end portion of the stud 59 by which the stud may be turned to raise the roll slightly as it is sometimes found advantageous to do when operating on work pieces of material which have a tendency to adhere to the table. A screw 54 is threaded vertically in the frame 22 so that its lower end abuts on the work table and is so adjusted as to allow the feed band to descend as close as possible to the abrasive tool without actually coming into contact therewith. A screw 56 is provided to lock the screw 54 in the adjusted position.

For the purpose of partially supporting the weight of the frame 22 and the feed band mechanism, so that the force with which the work piece is pressed against the abrasive tool as it is fed by the feed band can be controlled, the machine is provided with hydraulically perated means comprising a pair of interconnected piston and cylinder devices. The first device comprises a cylinder 58 secured to a side portion of the work table and having a bore 60 closed at its upper end. A cap 62 is secured on the lower end of the cylinder and has a bore 64 which is coaxial with the bore of the cylinder. Movably mounted in the bore is a piston 66, a stem 68 of which extends through the upper end of the cylinder and abuts against a face 70 on the forward end of the frame 22. The bore 64 is connected by a pipe 72 to a cap 74 of a similar second piston and cylinder device which is mounted on the bracket in an inverted position as compared with the first device. A stem 76 of the piston in the second device abuts against an end portion of a spring-biased lever 78 which is pivoted on a pin 80 carried by an arm 82 projecting from the bracket 20. The lever 78 is rectangular in cross section and has slidable thereon a block 84 to which is anchored the upper end of a relatively long spring 86, the lower end of which is anchored by adjustable means (not shown) to a lower portion of the column 2, so that the tension of the spring on the block may be changed as desired. The block 84 is readily movable along the lever 78 in relation to the pivot 80 so that the thrust of the lever on the end of the piston stem 76 may be quickly and easily varied by altering the degree of leverage employed. For this purpose a quick-threaded screw 88 is threaded through the block and has a neck by which it is journaled in a laterally extending lug 90 provided on the end of the lever 78. Endwise movement of the screw in the lug is prevented on the one side by the larger diameter of the threaded portion of the screw and on the other side by a handwheel 92 secured on a portion of the neck extending beyond the lug 90.

When the hydraulic system formed by the first and second piston and cylinder devices is filled with pressure fluid, the arrangement is such that if a thrust is applied to the end of the piston stem 76 an equivalent thrust is applied to the face 70 of the frame 22 by the stem 68. If the force applied is sufiicient, pressure fluid flows from the second piston and cylinder device to the first and the frame 22 is raised. By varying the position of the block 84 on the lever 78, a varying spring pressure is applied through the lever against the end of the piston stem 76 and a varying upward counterbalancing thrust is applied to the frame. This varies inversely the effective force with which the band 26 presses the work piece against the abrasive tool. In this manner the force with which the work piece is pressed against the abrasive tool can be preset between a maximum value given by the weight of the frame assembly and a minimum value which is almost nothing since the weight of the frame assembly can be wholly 'or partially counterbalanced. As the frame moves up and down, pressure fluid flows to and fro along the connecting pipe 72 from one cylinder to the other.

In order to minimize damage to the trailing end of a work piece due to the sudden dropping of the frame 22 and the feed band 26 immediately after the work piece has passed the highest point of the abrasive tool, a valve unit 94 is inserted in the pipe line 72. This valve unit allows unimpeded flow of pressure fluid from the second cylinder to the first (i.e. when the frame is rising) but restricts the flow in the opposite direction, so that the downward movement of the feed band is retarded. By this means the trailing end of the work piece cannot he suddenly pushed downward by the falling feed band into further contact with the falling periphery of the abrasive tool, thus avoiding damage to the work piece.

Having thus described our invention, what we claim as new and desire to secure by- Letters Patent of the United States is:

1. In a machine for abrading work pieces of sheet material, a pair of opposed rolls comprising an abrading roll and a feed roll between which a work piece is fed,

means mounting one of said rolls for movement under the force of gravity toward the other roll, means for applying an opposing force to counteract at least partially the force of gravity acting on said one roll and thereby determine the effective force by which the work piece is pressed against the abrading roll, said force applying means comprising a first piston and cylinder device engageable with said mounting means, a second piston and cylinder device engageable with a lever, a conduit connecting the cylinders of both devices for forming a closed fluid circuit by which force applied through said lever to said second device is transmitted to said first device and applied to said mounting means, means for causing the lever to exert a force against said second device, and means for adjusting the degree of leverage of said lever for varying the force applied to said second device thereby also varying the effective force by which the work piece is pressed against the abrading roll.

2. In a machine for abrading work pieces of sheet material, a pair of opposed rolls comprising an abrading roll and a feed roll between which a work piece is fed, means mounting one of said rolls for movement under the force of gravity toward the other roll, means for applying an opposing force to counteract at least partially the force of gravity acting on said one roll and thereby determine the effective force by which the work piece is pressed against the abrading roll, said force applying means comprising a first piston and cylinder device engageable with said mounting means, a second piston and cylinder device engageable with a lever, a conduit connecting the cylinders of both devices for forming a closed fluid circuit by which force applied through said lever to said second device is transmitted to said first device and applied to said mounting means, a spring connected to an arm of said lever for causing the lever to exert a force against said second device, and means for adjusting the connection of the spring along said arm for varying the force applied by the lever to the second device thereby also varying the effective force by which the work piece is pressed against the abrading roll.

3. In a machine for abrading work pieces of sheet material, a pair of opposed rolls comprising an abrading roll and a feed roll between which a work piece is fed, means mounting one of said rolls for movement under the force of gravity toward the other roll, means for applying an opposing force to counteract at least partially the force of gravity acting on said one roll and thereby determine the effective force by which the work piece is pressed against the abrading roll, said force applying means comprising a first piston and cylinder device engageable with said mounting means, a second piston and cylinder device engageable with a lever, a conduit connecting the cylinders of both devices for forming a closed fluid circuit by which force applied through said lever to said second device is transmitted to said first device and applied to said mounting means, means for causing the lever to exert a force against said second device, means for adjusting the degree of leverage of said lever by varying the force applied to said second device thereby also varying the eifective force by which the work piece is pressed against the abrading roll, and a valve in said conduit permitting free flow of fluid in one direction from the second device to the first device so that said opposing force is not restricted, said valve also restricting the flow of fluid in the opposite direction from the first device to the second device for retarding the movement of said one roll toward the other roll under the force of gravity thereby preventing sudden dropping of said one roll as the work piece is fed beyond the bite of said rolls.

4. In a machine for abrading work pieces of sheet material, a pair of opposed rolls comprising an abrading roll and a feed roll between which a work piece is fed, means mounting one of said rolls for movement under the force of gravity toward the other roll, means for applying an opposing force to counteract at least partially the force of gravity acting on said one roll and thereby determine the eifective force by which the work piece is pressed against the abrading roll, said force applying means comprising a first piston and cylinder device engageable with said mounting means, a second piston and cylinder device engageable with a lever, a conduit connecting the cylinders of both devices for forming a closed fluid circuit by which force applied through said lever to said second de vice is transmitted to said first device and applied to said mounting means, a spring connected to an arm of said lever for causing the lever to exert a force against said second device, means for adjusting the connection of the spring along said arm for varying the force applied by the lever to the second device thereby also varying the effective force by which the work piece is pressed against the abrading roll, and a valve in said conduit permitting free flow of fluid in one direction from the second device to the first device so that said opposing force is not restricted, said valve also restricting the flow of fluid in the opposite direction from the first device to the second device for retarding the movement of said one roll toward the other roll under the force of gravity thereby prevent- 6 ing sudden dropping of said one roll as the work piece is fed beyond the bite of said rolls.

5. In a machine for abrading work pieces of sheet material, a pair of opposed rolls comprising an abrading roll and a feed roll between which a Work piece is fed, means mounting one of said rolls for movement under the force of gravity toward the other roll, means for applying an opposing force to counteract at least partially the force of gravity acting on said one roll and thereby determine the efifective force by which the work piece is pressed against the abrading roll, said force applying means comprising a first piston and cylinder device engageable with said mounting means, a second piston and cylinder device engageable with a lever, a conduit connecting the cylinders of both devices for forming a closed fluid circuit by which force applied through said lever to said second device is transmitted to said first device and applied to said mounting means, a block mounted on an arm of said lever, a spring connected to said block for causing the lever to exert a force against said second device, and means for adjusting said block along said arm. toward and away from the fulcrum of the lever for varying the force applied to said second device thereby also varying the effective force by which the work piece is pressed against the abrading roll.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN A MACHINE FOR ABRADING WORK PIECES OF SHEET MATERIAL, A PAIR OF OPPOSED ROLLS COMPRISING AN ABRADING ROLL AND A FEED ROLL BETWEEN WHICH A WORK PIECE IS FED, MEANS MOUNTING ONE OF SAID ROLLS FOR MOVEMENT UNDER THE FORCE OF GRAVITY TOWARD THE OTHER ROLL, MEANS FOR APPLYING AN OPPOSING FORCE TO COUNTERACT AT LEAST PARTIALLY THE FORCE OF GRAVITY ACTING ON SAID ONE ROLL AND THEREBY DETERMINE THE EFFECTIVE FORCE BY WHICH THE WORK PIECE IS PRESSED AGAINST THE ABRADING ROLL, SAID FORCE APPLYING MEANS COMPRISING A FIRST PISTON AND CYLINDER DEVICE ENGAGEABLE WITH SAID MOUNTING MEANS, A SECOND PISTON AND CYLINDER DEVICE ENGAGEABLE WITH A LEVER, A CONDUIT CONNECTING THE CYLINDERS OF BOTH DEVICES FOR FORMING A CLOSED FLUID CIRCUIT BY WHICH FORCE APPLIED THROUGH SAID LEVER TO SAID SECOND DEVICE IS TRANSMITTED TO SAID FIRST DEVICE AND APPLIED TO SAID MOUNTING MEANS, MEANS FOR CAUSING THE LEVER TO EXERT A FORCE AGAINST SAID SECOND DEVICE, AND MEANS FOR ADJUSTING THE DEGREE OF LEVERAGE OF SAID LEVER FOR VARYING THE FORCE APPLIED TO SAID SECOND DEVICE THEREBY ALSO VARYING THE EFFECTIVE FORCE BY WHICH THE WORK PIECE IS PRESSED AGAINST THE ABRADING ROLL. 